In the stereo encoding technology, a left channel signal and a right channel signal are downmixed into a first monophonic signal, energy relations between the first monophonic signal and the left and the right channel signals are encoded, the first monophonic signal is adjusted to obtain a second monophonic signal, and differences between the second monophonic signal and the left channel signal and between the second monophonic signal and the right channel signal are encoded respectively. The information may be used to reconstruct audio signals at the decoding end to obtain a good stereo effect.
In the existing stereo encoding technology, the first monophonic signal needs to be adjusted only when a scaling factor is determined. In order to determine an optimal scaling factor, all possible scaling factors are calculated and compared in the prior art. Therefore, high calculation amount and complexity are required, and many system resources are occupied.